This invention relates generally to continuous flow lubricated bearings for rotating shafts of large machinery and in particular to oil deflector apparatus which prevents oil leakage from the housings of these bearings.
Journal bearings for large rotary machines (e.g., large steam turbines) are provided with a continuous flow of lubricating oil according to a technique often referred to as "flood lubrication". Although the bulk of the lubricating oil flowing through a bearing is confined to the bearing housing, a certain amount does escape, with a portion of the leakage traveling axially along the rotating shaft. To confine this oil, oil deflector sealing arrangements are provided around the shaft adjacent certain of the bearings. The oil deflector generally includes a labyrinth seal having seal rings, or "teeth", and an oil collection means for trapping and draining off to the lubricating oil reservoir any oil traveling along the shaft.
A problem with oil deflector apparatus (particularly with machines operating at elevated temperatures, such as a steam turbine) has resulted from the carbonization of oil within the oil deflector apparatus and a buildup of solid carbonization products within the teeth of the seal. In some instances the carbonization problem has been severe enough to cause damage to the shaft, producing machine vibrations to the point that the machine has become inoperable. For a large steam turbine of the type used in the generation of electrical power on a commercial scale, machine outages are very costly and provisions for guarding against such situations are continually being sought.
Investigations have shown that the degree of oil carbonization within oil deflector apparatus is directly related to the temperature of the apparatus; the higher the temperature, the more likelihood there is of carbonization occurring. Although radiant heat shields are commonly utilized to guard the deflector from heat radiated by nearby high temperature components, they have not been entirely successful in overcoming the carbonization problems.
It is, therefore, among the objects of the present invention to provide oil deflector apparatus which overcomes those problems outlined above. Further, and more particularly, it is an object of the present invention to provide an oil deflector which is fluidly cooled continuously during machine operation and which lends itself to cooling by oil drawn from the supply providing oil for bearing lubrication.
Still further objects and advantages of the invention will be apparent from the ensuing description.